2003 YAMAHA YZ450F start stop button

GEN
INFO

1 - 1
DESCRIPTION
EC100000
GENERAL INFORMATION
EC110000
DESCRIPTION
1
Clutch lever
2
Hot starter lever
3
Front brake lever
4
Throttle grip
5
Radiator cap
6
Fuel tank cap
7
“ENGINE STOP” button
8
Kick starter
9
Fuel tank
0
Radiator
A
Coolant drain bolt
B
Rear brake pedal
C
Valve joint
D
Fuel cock
E
Cold starter knob
F
Drive chain
G
Air cleaner
H
Shift pedal
I
Oil dipstick
J
Front fork
NOTE:


The machine you have purchased may differ
slightly from those shown in the following.

Designs and specifications are subject to
change without notice.

1 - 10
GEN
INFO
CONTROL FUNCTIONS
EC150000
CONTROL FUNCTIONS
EC151000
“ENGINE STOP” BUTTON
The “ENGINE STOP” button 1 is located on
the left handlebar. Continue pushing the
“ENGINE STOP” button till the engine comes
to a stop.
EC152000
CLUTCH LEVER
The clutch lever 1 is located on the left han-
dlebar; it disengages or engages the clutch.
Pull the clutch lever to the handlebar to disen-
gage the clutch, and release the lever to
engage the clutch. The lever should be pulled
rapidly and released slowly for smooth starts.
EC153000
SHIFT PEDAL
The gear ratios of the constant-mesh 4 speed
transmission are ideally spaced. The gears
can be shifted by using the shift pedal 1 on
the left side of the engine.
EC154000
KICK STARTER
Rotate the kick starter 1 away from the
engine. Push the starter down lightly with your
foot until the gears engage, then kick smoothly
and forcefully to start the engine. This model
has a primary kick starter so the engine can be
started in any gear if the clutch is disengaged.
In normal practices, however, shift to neutral
before starting.
1
EC155001
THROTTLE GRIP
The throttle grip 1 is located on the right han-
dlebar; it accelerates or decelerates the
engine. For acceleration, turn the grip toward
you; for deceleration, turn it away from you.

1 - 21
GEN
INFO
BREAK-IN PROCEDURES
1. Before starting the engine, fill the fuel
tank with the fuel.
2. Perform the pre-operation checks on the
machine.
3. Start and warm up the engine. Check the
idle speed, and check the operation of
the controls and the “ENGINE STOP”
button. Then, restart the engine and
check its operation within no more than 5
minutes after it is restarted.
4. Operate the machine in the lower gears
at moderate throttle openings for five to
eight minutes.
5. Check how the engine runs when the
motorcycle is ridden with the throttle 1/4
to 1/2 open (low to medium speed) for
about one hour.
6. Restart the engine and check the opera-
tion of the machine throughout its entire
operating range. Restart the machine
and operate it for about 10 to 15 more
minutes. The machine will now be ready
to race.
CAUTION:
After the break-in or before each race,
you must check the entire machine for
loose fittings and fasteners as per
“TORQUE-CHECK POINTS”.
Tighten all such fasteners as required.
When any of the following parts have
been replaced, they must be broken in.
CYLINDER AND CRANKSHAFT:
About one hour of break-in operation is
necessary.
PISTON, RING, VALVES, CAMSHAFTS
AND GEARS:
These parts require about 30 minutes of
break-in operation at half-throttle or less.
Observe the condition of the engine care-
fully during operation.
STARTING AND BREAK-IN

2 - 21
SPEC

CABLE ROUTING DIAGRAM
EC240000
CABLE ROUTING DIAGRAM
1
Fuel tank breather hose
2
Hot starter cable
3
Radiator hose 4
4
Cylinder head breather hose
5
Radiator hose 1
6
Oil tank breather hose
7
Hose guide
8
Brake hose
9
“ENGINE STOP” button lead
0
Clamp
A
Sub wire harness
B
TPS (throttle position sen-
sor) lead
C
Neutral switch lead
D
Oil hose
E
Radiator breather hose
F
CDI magneto lead
G
Carburetor breather hose
H
Overflow hose
Å
Pass the fuel tank breather hose
between the handlebar and ten-
sion bar, then insert its end into
the hole of the number plate.
ı
Pass the hot starter cable
between the cylinder head
breather hose, oil tank breather
hose and ignition coil, then on
the outside of the left engine
bracket.
Ç
Pass the cylinder head breather
hose on the outside of the radia-
tor hose 1 and on the inside of the
radiator pipe (radiator hose 4).
Î
Fit the brake hose into the
guides on the protector.
‰
Fasten the “ENGINE STOP”
button lead and sub wire har-
ness to the frame with a plastic
locking tie and cut off the tie
end.
ÏFasten the sub wire harness
and hot starter cable to the
frame at the white tape for the
sub wire harness with a plastic
locking tie and cut off the tie
end.
ÌFasten the sub wire harness to
the frame with a plastic locking
tie and cut off the tie end.
C
9
0
A
0
0
0
0
0
B
C
D
0 0 E 0 F 0
1
2 8
7
6
5
4
3GHG9A
D
E
C
B
A
A
C
BB
Ç ÎÅ
ıØ
˜ ˆ
Ò
Ô ÈÌ Ó Ì Ï ‰ ‰
∏
*
*

2 - 25
SPECCABLE ROUTING DIAGRAM
1Throttle cable
2Fuel tank breather hose
3Clamp
4Clutch cable
5Hot starter cable
6“ENGINE STOP” button lead
7Brake hose
8Hose guideÅFasten the “ENGINE STOP” but-
ton lead to the handlebar with the
plastic band.
ıPass the brake hose in front of the
number plate.
ÇPass the hot starter cable, clutch
cable and throttle cables through
the cable guide.
*Decompression cable (supplied
for Europe and optional for other
destinations)
1
23
4
5
6
7
83
6 Å
Çı
40˚±10˚
A
A
*

5 - 39
CHAS
EC5B0000
HANDLEBAR
Extent of removal:1 Handlebar removal
Extent of removal Order Part name Q’ty Remarks
Preparation for removalHANDLEBAR REMOVAL
Number plate Remove the clamp portion only.
1 Hot starter cable 1 Disconnect at the lever side.
2 Hot starter lever holder 1
3 Clutch cable 1 Disconnect at the lever side.
4 Clutch lever holder 1
5“ENGINE STOP” button 1
6 Master cylinder 1 Refer to “REMOVAL POINTS”.
7 Throttle cable cap 1
8 Throttle cable #2 (pushed) 1 Disconnect at the throttle side.
9 Throttle cable #1 (pulled) 1 Disconnect at the throttle side.
10 Grip (right) 1 Refer to “REMOVAL POINTS”.
11 Tube guide 1
12 Cover (grip cap) 1
13 Collar 1
14 Grip (left) 1 Refer to “REMOVAL POINTS”.
15 Handlebar holder (upper) 2
16 Handlebar 1
1
HANDLEBAR

5 - 43
CHASHANDLEBAR
8. Install:
Master cylinder 1
Master cylinder bracket 2
Bolt (master cylinder bracket) 3
NOTE:
Install the bracket so that the arrow mark a
faces upward.
First tighten the bolt on the upper side of the
master cylinder bracket, and then tighten the
bolt on the lower side.
9. Install:
“ENGINE STOP” button 1
Clutch lever holder 2
Bolt (clutch lever holder) 3
Hot starter lever holder 4
Bolt (hot starter lever holder) 5
Clamp 6
NOTE:
The “ENGINE STOP” button, clutch lever
holder and clamp should be installed accord-
ing to the dimensions shown.
Pass the “ENGINE STOP” button lead in the
middle of the clutch lever holder.
T R..9 Nm (0.9 m · kg, 6.5 ft · lb)
T R..4 Nm (0.4 m · kg, 2.9 ft · lb)
T R..4 Nm (0.4 m · kg, 2.9 ft · lb)
10. Install:
Clutch cable 1
Hot starter cable 2
NOTE:
Apply the lithium soap base grease on the
clutch cable end and hot starter cable end.
11. Adjust:
Clutch lever free play
Refer to “CLUTCH ADJUSTMENT”
section in the CHAPTER 3.
Hot starter lever free play
Refer to “HOT STARTER LEVER
ADJUSTMENT” section in the CHAP-
TER 3.

6 - 4
–+ELEC

IGNITION SYSTEM
SPARK GAP TEST
1. Disconnect the ignition coil from spark
plug.
2. Remove the ignition coil cap.
3. Connect the dynamic spark tester
1
(ignition checker
2
) as shown.

Ignition coil
3


Spark plug
4

Å
For USA and CDN
ı
Except for USA and CDN
4. Kick the kick starter.
5. Check the ignition spark gap.
6. Start engine, and increase spark gap until
misfire occurs. (for USA and CDN only)
Minimum spark gap:
6.0 mm (0.24 in)
Å
ı

COUPLERS, LEADS AND IGNITION COIL
CONNECTION INSPECTION
1. Check:

Couplers and leads connection
Rust/dust/looseness/short-circuit
→

Repair or replace.

Ignition coil and spark plug as they are
fitted
Push in the ignition coil until it closely
contacts the spark plug hole in the cyl-
inder head cover.
EC625001
“ENGINE STOP” BUTTON INSPECTION
1. Inspect:

“ENGINE STOP” button conduct
No continuity while being pushed
→
Replace.
Continuity while being freed
→
Replace.
Tester (+) lead
→
Black/White lead
1

Tester (–) lead
→
Black lead
2

B/W
1
B
2
Tester selec-
tor position
PUSH IN
Ω

×
1
FREE
B/W B
11 2 2